The pelvis as a whole

The pelvis is formed by the connecting pelvic bones and the sacrum. It is a bone ring. The pelvis is the receptacle for many internal organs. With the help of the pelvic bones, the torso is connected with the lower limbs. There are two divisions - a large and a small pelvis.

A large pelvis (pelvis major) is delimited from the lower pelvis below the borderline. The border line (linea terminalis) passes through the cape of the sacrum, along the arcuate lines of the ileum, the crests of the pubic bones, and the upper margin of the pubic symphysis. The large pelvis behind the body is bounded by the body of the V lumbar vertebra, from the sides by the wings of the iliac bones. There is no large bone in the front of the front.

Small pelvis (pelvis minor) behind is limited by the pelvic surface of the sacrum and the ventral surface of the coccyx. On the side of the pelvic wall are the inner surface of the pelvic bones (below the boundary line), sacro-awned and sacro-ligamentous ligaments. The anterior wall of the small pelvis is the upper and lower branches of the pubic bones, pubic symphysis.

The small pelvis has an inlet and an outlet. The upper aperture (apertura pelvis superior) is bordered by the borderline. Exit from the pelvis - the lower aperture of the pelvis (apertura pelvis inferior) behind is limited by the coccyx, from the sides of the sacro-ligament ligaments, the branches of the ischium bones, the ischial tuber, the lower branches of the pubic bones, and in front - the pubic symphysis. The occlusion aperture located in the lateral walls of the small pelvis is covered by a fibrous obturatoria. Leaping through the locking groove, the membrane limits the canalis (canalis obturatorius). Through it, from the cavity of the small pelvis, the vessels and nerve pass to the thigh. In the side walls of the small pelvis there are also large and small sciatic holes. The large sciatic foramen (foramen ischiadicum majus) is limited by a large sciatic notch and a sacro-osteous ligament. A small sciatic foramen (foramen ischiadicum minus) is formed by a small sciatic notch, sacro-tubercular and sacro-ovarous ligaments.

The structure of the pelvis is associated with the sex of the person. The upper aperture of the pelvis with the vertical position of the body in women forms with an horizontal plane an angle of 55-60 °. The pelvis in women is lower and wider, the sacrum is wider and shorter than in men. Cape of the sacrum of women is less forward. The sciatic mounds are more extended in sides, the distance between them is greater than that of men. The angle of convergence of the lower branches of the pubic bones in women is 90 ° (pubic arch), in men it is 70-75 ° (sublip angulation).

To predict the birth process, it is important to know the size of the woman's pelvis. Practical importance is the size of both small and large pelvis. The distance between the two upper and anterior iliac spines (distantia spinarum) in women is 25-27 cm. The distance between the farthest points of the iliac bones (distantia cristarum) is 28-30 cm.

The direct size of the entrance to the small pelvis (true, or gynecological, conjugata-conjugata vera, s. Gynaecologica) is measured between the cape of the sacrum and the most protruding posterior point of the pubic symphysis. This size is 11 cm.

The transverse diameter (diameter transversa) of the entrance to the small pelvis - the distance between the most distant points of the boundary line - is 13 cm.

The oblique diameter (diameter obliqua) of the entrance to the small pelvis is 12 cm. It is measured between the sacroiliac joint of one side of the pelvis and the iliac-pubic elevation of the other side.